diff --git a/StorageBundle/Adaptors/S3Storage.php b/StorageBundle/Adaptors/S3Storage.php
index 9f48b61..4376820 100644
--- a/StorageBundle/Adaptors/S3Storage.php
+++ b/StorageBundle/Adaptors/S3Storage.php
@@ -3,6 +3,7 @@
 namespace Bluesquare\StorageBundle\Adaptors;
 
 use Aws\S3\S3Client;
+use Symfony\Component\Config\Definition\Exception\Exception;
 
 /**
  * Interface de manipulation du stockage S3
@@ -18,10 +19,16 @@ class S3Storage
     protected $bucket;
     protected $region;
 
+    private $required_config_field = ['bucket', 'region', 'endpoint', 'credientials'];
+
     public function __construct ($storage_name, $config)
     {
         // TODO: on check la présence de "bucket", "region", "endpoint", "credentials" ("key", "secret") dans $config
 
+        if ($this->configIsNotNormed($config))
+            throw new Exception("Error from config file :(");
+//        if (isset($config['bucket']) && isset($config))
+
         $this->config = $config;
         $this->bucket = $config['bucket'];
 
@@ -36,6 +43,12 @@ class S3Storage
         ]);
     }
 
+    private function configIsNotNormed($config)
+    {
+        dump(array_diff($this->required_config_field, $config)); die;
+//        return ()
+    }
+
     protected function getPrefix($prefix = null)
     {
         $ret = '';
diff --git a/StorageBundle/DependencyInjection/Configuration.php b/StorageBundle/DependencyInjection/Configuration.php
index b643483..22db9e0 100644
--- a/StorageBundle/DependencyInjection/Configuration.php
+++ b/StorageBundle/DependencyInjection/Configuration.php
@@ -20,14 +20,14 @@ class Configuration implements ConfigurationInterface
         $root->useAttributeAsKey('storage_name')
             ->prototype('array')
                 ->children()
-                    ->scalarNode('type')->isRequired()->cannotBeEmpty()->end()
-                    ->scalarNode('bucket')->isRequired()->cannotBeEmpty()->end()
-                    ->scalarNode('region')->isRequired()->cannotBeEmpty()->end()
-                    ->scalarNode('endpoint')->isRequired()->cannotBeEmpty()->end()
+                    ->scalarNode('type')->end()
+                    ->scalarNode('bucket')->end()
+                    ->scalarNode('region')->end()
+                    ->scalarNode('endpoint')->end()
                     ->arrayNode('credentials')
                         ->children()
-                            ->scalarNode('key')->isRequired()->cannotBeEmpty()->end()
-                            ->scalarNode('secret')->isRequired()->cannotBeEmpty()->end()
+                            ->scalarNode('key')->end()
+                            ->scalarNode('secret')->end()
                         ->end()
                     ->end()
                     ->scalarNode('version')->end()